Fluid distributor for a microchannel heat exchanger

ABSTRACT

Disclosed is a microchannel heat exchanger comprising an inlet header enclosing an inlet header volume and comprising an inlet port, and wherein the inlet header extends along a first direction; an outlet header; a plurality of microchannel tubes extending between, and fluidly connecting the inlet header and the outlet header; and a flow distribution conduit extending into the inlet header volume, interposed between, and in fluid communication with, the inlet port and the plurality of microchannel tubes and wherein the flow distribution conduit is configured to direct a fluid flowing therethrough along the first direction.

CROSS REFERENCE TO A RELATED APPLICATION

The application claims the benefit of U.S. Provisional Application No. 63/269,787 filed Mar. 23, 2022, the contents of which are hereby incorporated in their entirety.

BACKGROUND

Exemplary embodiments pertain to the art of heat exchangers. More particularly, the present disclosure relates to configurations of fluid distributors for microchannel heat exchangers.

Microchannel heat exchanger performance can be dependent on fluid distribution through the heat exchanger core. Good refrigerant flow distribution, e.g., such as where all flow paths through the heat exchanger receive nearly equal amount of the total flow, is a key element to ensuring the entire heat exchanger is used equivalently for the heat transfer. Current distribution methods require complex distributor tubes with unique geometric configurations. These distributor tubes add increased cost and complexity of the heat exchangers. Accordingly, there remains a need for fluid distributors capable of providing good fluid distribution in heat exchangers that mitigate the cost and complexity associated with existing solutions.

BRIEF DESCRIPTION

Disclosed is a microchannel heat exchanger comprising an inlet header enclosing an inlet header volume and comprising an inlet port, and wherein the inlet header extends along a first direction; an outlet header; a plurality of microchannel tubes extending between, and fluidly connecting the inlet header and the outlet header; and a flow distribution conduit extending into the inlet header volume, interposed between, and in fluid communication with, the inlet port and the plurality of microchannel tubes and wherein the flow distribution conduit is configured to direct a fluid flowing therethrough along the first direction.

In accordance with additional or alternative embodiments, wherein the flow distribution conduit comprises the terminal end of a heat exchanger inlet pipe fluidly connecting the microchannel heat exchanger to a refrigerant containing system.

In accordance with additional or alternative embodiments, wherein the heat exchanger inlet pipe comprises a bend adjacent the flow distribution conduit.

In accordance with additional or alternative embodiments, wherein an angle of the bend is greater than or equal to 30 degrees and less than or equal to 150 degrees.

In accordance with additional or alternative embodiments, wherein the inlet header further comprises an inlet header length extending in the first direction and the flow distribution conduit extends into the inlet header volume an extension distance and wherein the extension distance is between 1% and 99%, endpoint inclusive, of the inlet header length.

In accordance with additional or alternative embodiments, wherein the extension distance is between 5% and 75%, endpoint inclusive, of the inlet header length.

In accordance with additional or alternative embodiments, wherein the extension distance is between 5% and 50%, endpoint inclusive, of the inlet header length.

In accordance with additional or alternative embodiments, wherein the flow distribution conduit comprises a flow distribution conduit inlet, a flow distribution conduit body, and a flow distribution conduit outlet, and wherein the flow distribution conduit body is impervious and configured without holes therethrough.

In accordance with additional or alternative embodiments, further comprising a hydraulic diameter ratio of the hydraulic diameter of the flow distribution conduit divided by the hydraulic diameter of the inlet header, and wherein the hydraulic diameter ratio is greater than or equal to 0.05 and less than or equal to about 0.95.

In accordance with additional or alternative embodiments, wherein the plurality of microchannel tubes comprises a bend or a fold such that the heat exchanger comprises a V shape, U shape, or A shape.

In accordance with additional or alternative embodiments, further comprising a turbulator disposed in the inlet header volume.

In accordance with additional or alternative embodiments, wherein the flow distribution conduit comprises a converging section and a throat.

In accordance with additional or alternative embodiments, wherein the microchannel heat exchanger is configured as an evaporator of a vapor compression cycle.

In accordance with additional or alternative embodiments, wherein the flow distribution conduit is positioned offset from a centerline of the inlet header volume.

In accordance with additional or alternative embodiments, wherein the offset is less than or equal to half the distance between the centerline of the inlet header volume and a wall of the inlet header.

In accordance with additional or alternative embodiments, wherein the inlet header and the flow distribution conduit are substantially cylindrical in shape.

Further disclosed is a vapor compression system comprising a compressor, an evaporator, a condenser, and an expansion valve, wherein the evaporator comprises the microchannel heat exchanger in accordance with additional or alternative embodiments.

Further disclosed is a method of distributing fluid in a heat exchanger comprising providing a heat exchanger having an inlet header, an outlet header, and a plurality of microchannel tubes interposed between, and disposed in fluid communication with, the inlet header and the outlet header, wherein the inlet header comprises a fluid distribution conduit disposed between, and in fluid communication with, an inlet port and the plurality of microchannel tubes; jetting a refrigerant flow through the fluid distribution conduit into an inlet header volume of the inlet header; reflecting at least a portion of the refrigerant flow off an end cap of the inlet header; creating a shearing flow between the jetting flow and the reflecting flow thereby causing turbulent flow within the inlet header volume.

In accordance with additional or alternative embodiments, further comprising jetting the refrigerant flow through the fluid distribution conduit at a first temperature; and returning the refrigerant flow to the refrigerant system at a second temperature, wherein the second temperature is greater than the first temperature.

In accordance with additional or alternative embodiments, further comprising changing the direction of the fluid flow before passing it through the fluid distribution conduit by forcing it through a bent section of pipe adjacent the fluid distribution conduit.

Technical effects of embodiments of the present disclosure include improved fluid distribution through a core of a microchannel heat exchanger which enables, on average, improvements in capacity of3.0% and energy efficiency rating at full load of 2.6% for 1.5-ton to 5.0-ton air conditioning systems.

The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, that the following description and drawings are intended to be illustrative and explanatory in nature and non-limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

FIG. 1 is a schematic illustration of a cross-sectional view of an exemplary single slab microchannel heat exchanger having a fluid distribution conduit, in accordance with one or more embodiments of the disclosure.

FIG. 2 is a schematic illustration of a side view of an exemplary V-shaped microchannel heat exchanger having a fluid distribution conduit, in accordance with one or more embodiments of the disclosure.

FIG. 3 is a schematic illustration of a three-dimensional view of an exemplary V shaped microchannel heat exchanger having a fluid distribution conduit, in accordance with one or more embodiments of the disclosure.

FIG. 4 is a schematic illustration of the detail A views from FIGS. 1-2 , in accordance with one or more embodiments of the disclosure.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

FIG. 1 is a schematic illustration of a microchannel heat exchanger 100 having an inlet header 10, an outlet header 20, and a plurality of microchannel tubes 30 extending therebetween, and fluidly connecting the inlet header 10 and the outlet header 20. The microchannel heat exchanger 100 can include a plurality of heat transfer fins 40 which can be disposed between adjacent tubes of the plurality of microchannel tubes 30 along at least portion of the heat exchanger 100. The inlet header 10 can enclose an inlet header volume 12 and can include an inlet port 11 which can be fluidly connected to a refrigerant system (e.g., air conditioning, heat pump, refrigeration, or like system) by a heat exchanger inlet conduit 80 to provide a refrigerant flow 82 to the heat exchanger 100 during operation of the system. The inlet header 10 can have an inlet header length H extending along a first direction 1, e.g., the 1-dimension in the attached figures.

The inlet header 10 can include a flow distribution conduit 50 extending into the inlet header volume 12. The flow distribution conduit 50 can be interposed between, and in fluid communication with, the inlet port 11 and the plurality of microchannel tubes 30. The flow distribution conduit 50 can extend from, or through, the inlet port 11 and into the inlet header volume 12 and can be configured to direct a fluid (e.g., refrigerant) flowing therethrough along the first direction 1 (e.g., along the length dimension of the header). The flow distribution conduit 50 can extend a distance D into the inlet header volume 12 (which may be referred to herein an extension distance).

FIG. 2 is a schematic illustration of the microchannel heat exchanger 100 where the plurality of tubes 30 include a bend 36 along their length. Although the heat exchanger 100 can be formed into a single slab shape as in FIG. 1 , including a bend allows for additional shapes. For example, with a bend 36 disposed in the plurality of microchannel tubes 30, the outlet header 20 can be disposed along the same side and/or near the inlet header 10, such as in a V-shaped, U-shaped, A-shaped, or like configuration. The section of the heat exchanger 100 within the bent region 38, and adjacent thereto, can be free of heat transfer fins 40 to allow for twisting of the tubes of the plurality of microchannel tubes 30 within, and adjacent to, the bent region 38.

FIG. 3 is a schematic illustration of the microchannel heat exchanger 100 in a V-shaped configuration. The inlet header 10 can be positioned at the same vertical height (e.g., as determined along the h-dimension in the attached figures) as the outlet header 20 and the plurality of microchannel tubes 30 can include a bend 36. In this configuration the plurality of microchannel tubes 30 can extend out of the first header 10 along a second direction 2 (e.g., perpendicular to the first direction 1) and into the outlet header 20 along a third direction 3. Furthermore, the second direction 2 can be unequal to the third direction 3. Alternatively, the second direction 2 and the third direction 3 can be symmetric about a center-plane extending through the bend 36 (e.g., extending through a center point of the bend 36 in the 1-h plane), such that the magnitude of the angle between the second direction 2 and the center-plane and magnitude of the angle between the third direction 3 and the center-plane are about equal.

The inlet header 10 and outlet header 20 can have any cross-sectional shape (e.g., shape in the h-w plane in the attached figures). For example, the inlet header 10 and/or outlet header 20 can have a circular, oval, square, half-circle, half-oval, or any non-self-intersecting closed polygonal cross-sectional shape with straight or curved edges. The cross-sectional shape of the inlet header 10 and the outlet header 20 can be different or can be the same. The inlet header 10 and/or the outlet header 20 can be constructed of header walls extending longitudinally (e.g., in the 1-axis dimension in the attached figures) with an end cap 13 fluidly sealing either end thereby enclosing the respective inlet header volume 12 and outlet header volume 22. The headers can include slots along their lengths for receiving the plurality of microchannel tubes 30 and can include a port for transferring fluid into or out of the header. The inlet header 10 can include an inlet port 11 (e.g., shown in FIG. 4 ). The inlet port 11 can be disposed through an end cap 13 or can be disposed through a wall of the inlet header 10. For example, an extrusion can form the walls of the header and an end cap 13 including the inlet port 11 can be positioned inside the header and sealed against the interior walls of the extrusion (e.g., such as in a welding or brazing operation).

Referring now to FIG. 4 , the inlet header 10 can have an inlet header centerline 15 extending along the geometric center of the inlet header 10. The flow distribution conduit 50 can have a flow distribution conduit centerline 55 extending along the geometric center the flow distribution conduit 50. The flow distribution conduit 50 can be disposed such that the flow distribution conduit centerline 52 is coincident with the inlet header centerline 15. Alternatively, the flow distribution conduit 50 can be disposed such that the flow distribution conduit centerline 55 is shifted by an offset distance X from the inlet header centerline 15. The offset distance X can be less than or equal to three-quarters the distance between the inlet header centerline 15 and an interior wall 18 of the inlet header 10. For example, the offset distance X can be less than or equal to about 75%, or less than or equal to about 60%, less than or equal to about 50%, less than or equal to about 40%, less than or equal to about 30%, or less than or equal to about 25% the distance between the inlet header centerline 15 and an interior wall 18 of the inlet header 10.

The flow distribution conduit 50 can be shifted in any direction relative to the inlet header centerline 15. For example, the flow distribution conduit 50 can be shifted away from inlets 38 to the plurality of microchannel tubes 30 (e.g., as in the positive direction along the h-dimension in the attached figures). In another example, the flow distribution conduit 50 can be shifted toward the inlets 38 of the plurality of microchannel tubes 30 (e.g., as in the negative direction along the h-dimension in the attached figures). In yet another example, the flow distribution conduit 50 can be shifted toward a side of the inlets 38 of the plurality of microchannel tubes 30 (e.g., as in the positive or negative direction along the w-dimension in the attached figures).

The flow distribution conduit 50 can have solid walls, e.g., such that no flow passages exist through the walls of the conduit. For example, the flow distribution conduit 50 can consist of an elongated hollow member having a length, and one inlet 51, and one outlet 52 disposed at either end of the elongated hollow member. The flow distribution conduit 50 can have any cross-sectional shape (e.g., shape in the h-w plane in the attached figures). For example, the flow distribution conduit 50 can have a circular, oval, square, half-circle, half-oval, or any non-self-intersecting closed polygonal cross-sectional shape with straight or curved edges. Moreover, the flow distribution conduit 50 can have a circular cross-sectional shape and can extend into the inlet header volume 12 as a cylindrical body having a single inlet 51 and a single outlet 52. The outlet 52 can be pointed in the first direction 1, along the length dimension of the inlet header 10, e.g., pointed at the opposing end cap 13. The shape of the flow distribution conduit 50 can correspond to the shape of the inlet header 10. In an example, both the flow distribution conduit 50 and the inlet header 10 can have a cylindrical shape.

The flow distribution conduit 50 can extend linearly into the inlet header volume 12 and parallel with the length dimension of the inlet header 10 (e.g., extending along the 1-dimension in the attached figures). The distance D that the flow distribution conduit 50 can extend into the inlet header volume 12 can be expressed as a percentage of the inlet header length H. When the flow distribution conduit 50 extends from an end cap 13 the distance D can be greater than or equal to about 2% of the header length H and less than or equal to about 95% of H. For example, the distance D can be from greater than or equal to about 2% of H to less than or equal to about 75% of H, or from greater than or equal to about 2% of H to less than or equal to about 50% of H, or from greater than or equal to about 5% of H to less than or equal to about 50% of H, or from greater than or equal to about 2% of H to less than or equal to about 30% of H, or from greater than or equal to about 5% of H to less than or equal to about 25% of H.

The distance the flow distribution conduit 50 can extend into the inlet header volume 12 can be expressed relative to the number of tubes of the plurality of microchannel tubes 30 the conduit has extended passed, e.g., as measured along the inlet header 10 length from the end cap 13. For example, the flow distribution conduit 50 can extend to between a first microchannel tube 31 and a second microchannel tube 32, or between the second microchannel tube 32 and a third microchannel tube 33, or between the third microchannel tube 33 and a fourth microchannel tube 34, or between any two adjacent microchannel tubes of the plurality of microchannel tubes 30. For example, the flow distribution conduit 50 can extend to about half the distance of the inlet header volume 12, e.g., passed about half of the microchannel tubes of the plurality of microchannel tubes.

A flow area ratio of the cross-sectional flow area of the flow distribution conduit 50 (e.g., such as the area in the h-w plane in the attached figures) divided by the cross-sectional flow area of the inlet header 10 (e.g., such as the area in the h-w plane in the attached figures) can be used to size the flow distribution conduit 50 for various sizes of microchannel heat exchangers 100. For example, the flow area ratio can be greater than or equal to about 0.01 and less than or equal to about 0.65, such as greater than or equal to about 0.01 and less than or equal to about 0.50, or greater than or equal to about 0.01 and less than or equal to about 0.45, or greater than or equal to about 0.01 and less than or equal to about 0.35, or greater than or equal to about 0.01 and less than or equal to about 0.25, or greater than or equal to about 0.02 and less than or equal to about 0.25, or greater than or equal to about 0.03 and less than or equal to about 0.25, or greater than or equal to about 0.04 and less than or equal to about 0.25, or greater than or equal to about 0.05 and less than or equal to about 0.25, or greater than or equal to about 0.05 and less than or equal to about 0.20, or greater than or equal to about 0.05 and less than or equal to about 0.15, or about 0.05, or about 0.06, or about 0.07, or about 0.08, or about 0.09, or about 0.10, or about 0.11, or about 0.12, or about 0.13, or about 0.14, or about 0.15.

A hydraulic diameter ratio of the hydraulic diameter of the flow distribution conduit 50 divided by the hydraulic diameter of the inlet header 10 can be used to size the flow distribution conduit 50 for various sizes of microchannel heat exchangers 100. For example, the hydraulic diameter ratio can be greater than or equal to about 0.05 and less than or equal to about 0.95, such as greater than or equal to about 0.10 and less than or equal to about 0.90, or greater than or equal to about 0.15 and less than or equal to about 0.85, or greater than or equal to about 0.15 and less than or equal to about 0.80, or greater than or equal to about 0.15 and less than or equal to about 0.75, or greater than or equal to about 0.15 and less than or equal to about 0.70, or greater than or equal to about 0.15 and less than or equal to about 0.65, or greater than or equal to about 0.15 and less than or equal to about 0.60, or greater than or equal to about 0.15 and less than or equal to about 0.55, greater than or equal to about 0.15 and less than or equal to about 0.50, greater than or equal to about 0.15 and less than or equal to about 0.45, greater than or equal to about 0.15 and less than or equal to about 0.40, or greater than or equal to about 0.15 and less than or equal to about 0.38, or greater than or equal to about 0.15 and less than or equal to about 0.36, or greater than or equal to about 0.15 and less than or equal to about 0.35, or greater than or equal to about 0.20 and less than or equal to about 0.35, or greater than or equal to about 0.20 and less than or equal to about 0.32, or about 0.15, or about 0.16, or about 0.17, or about 0.18, or about 0.19, or about 0.20, or about 0.21, or about 0.22, or about 0.23, or about 0.24 or about 0.25, or about 0.26, or about 0.27, or about 0.28, or about 0.29, or about 0.30, or about 0.31, or about 0.32, or about 0.33, or about 0.34, or about 0.35.

The header walls of the inlet header 10 can extend past one or both end caps 13 to form a partially enclosed portion 56 external to the inlet header volume 12. The partially enclosed portion 56 can include a notch 17 (e.g., a cut away section where the header wall has been removed) along a portion of the header to allow for closely coupling a heat exchanger inlet conduit 80 to the inlet port 11 of the inlet header 10. The partially enclosed portion 56 can also serve to protect the plumbing connection between to the inlet port 11 of the heat exchanger 100 during shipment and installation.

The heat exchanger inlet conduit 80 can fluidly connect the heat exchanger 100 to a refrigerant containing system, such as an air conditioner, heat pump, refrigeration system or the like. The heat exchanger inlet conduit 80 can include a bend 81 to direct fluid flowing therethrough into the fluid distribution conduit 50. The bend 81 can be disposed adjacent to the fluid distribution conduit 50. For example, the bend 81 can be disposed immediately upstream (e.g., in the negative 1-dimension of the attached figures) of the fluid distribution conduit 50. The bend 81 can include a bend angle a of less than or equal to about 180 degrees. For example, the bend angle a can be from about 30 degrees to about 180 degrees, such as a bend angle α of about 180 degrees, about 150 degrees, about 120 degrees, about 90 degrees (as shown in the attached figures), about 45 degrees, about 30 degrees, or the like. The heat exchanger inlet conduit 80 can extend parallel to the direction that the plurality of microchannel tubes 30 extend from the inlet header 10, e.g., along the second direction 2.

The microchannel heat exchanger 100 can be configured as an evaporator of a vapor compression system (e.g., refrigerant system), such as in an air conditioning, heat pump, or refrigeration system. For example, the heat exchanger inlet conduit 80 can be fluidly connected to the refrigerant system such that a refrigerant flow 82 is introduced into the inlet header 10, passes through the plurality of microchannel tubes 30 and is collected and exits the microchannel heat exchanger 100 through the outlet header 20. A second fluid, e.g., air, can be urged past the external surfaces of the microchannel heat exchanger 100 (e.g., along the plurality of microchannel tubes 30 and fins 40) to exchanger thermal energy with the refrigerant flow 82. The individual tubes of the plurality of microchannel tubes 30 can be flat tubes (e.g., having a major cross-sectional dimension greater than the minor cross-sectional dimension, such five times greater, or more). The microchannel tubes can include two or more parallel fluid conduits disposed longitudinally therethrough, e.g., such as formed from an extrusion process.

In an embodiment, the flow distribution conduit 50 can be formed from a terminal end of the heat exchanger inlet conduit 80 which fluidly connects the microchannel heat exchanger 100 to a refrigerant containing system. For example, the heat exchanger inlet conduit 80 can extend through the partially enclosed space 56, the inlet port 11 of the inlet header 10, and extend the distance D into the inlet header volume 12. In this way, the refrigerant flow can be jetted into the inlet header volume 12 where it can distribute evenly to the plurality of microchannel tubes 30.

In developing the disclosed microchannel heat exchanger distributor, the inventors have found that the system performance when the fluid distribution conduit 50 was implemented to be superior to other inlet distributor designs. For example, the performance of the presently disclosed fluid distribution conduit 50 was tested in air conditioning systems from designed for 1.5-ton to 5-ton cooling capacity. In these tests, system performance with the presently disclosed fluid distribution conduit 50 was compared to system performance with a distributor having multiple outlet ports disposed along its length (such as disclosed in U.S. patent application Ser. No. 16/860,236 which claims priority to U.S. Provisional Application No. 62/842,183), the inventors have found on average, about a 3% increase in system capacity, and 2.6% increase in Energy Efficiency Rating at full load (EER_(A)).

It is suspected that the jet action imparted to the refrigerant flow 82 by the fluid disturbing conduit 50 aids in equally distributing fluid to the plurality of microchannel tubes 30.

For example, flow turbulence resultant from fluid shear between the incoming jet 84 of refrigerant (from the outlet port 52 of the fluid distribution conduit 50) and reflected refrigerant flow 86 (e.g., reflected back toward the inlet port 11 from the far end cap 13) works to equalize the pressures along the length of inlet header volume 12 and equalize flow to the inlets 38 of the plurality of microchannel tubes 30. Accordingly, the microchannel heat exchanger 100 can optionally include a turbulator, such as a fluid shear imparting device (e.g., having multiple differently angled surfaces for disrupting laminar flow layers), disposed in the inlet header volume 12 to further aid imparting turbulence in fluid flowing through the inlet header volume 12. Moreover, to enhance the effect of the jet 84 of fluid exiting the outlet port 52, the fluid distribution conduit 50 can include a converging section and a throat to increase the fluid velocity as it traverses the fluid distribution conduit 50.

Methods of operating the microchannel heat exchanger 100 can include fluidly connecting the microchannel heat exchanger 100 to a vapor compression system (e.g., an air conditioning system, heat pump system, refrigeration device, or the like). For example, the heat exchanger inlet conduit 80 can be connected to the vapor compression system such that the microchannel heat exchanger 100 serves as an evaporator for the system. Furthermore, methods of operating the microchannel heat exchanger 100 can include flowing (e.g., creating a laminar jet 84 in the length dimension of the inlet header 10) the refrigerant flow 82 through the fluid distribution conduit 50 into an inlet header volume 12 of the inlet header 10. The methods of operating the microchannel heat exchanger 100 can include reflecting at least a portion of the jetted refrigerant flow 84 off an end cap 13 of the inlet header 10. For example, as the laminar jet 84 of refrigerant reaches the end cap 13 it can be reflected back toward the inlet port 11 (e.g., as shown in FIG. 2 ) as reflected refrigerant flow 86. This flow can interact with the adjacent jet 84 thereby creating a shearing flow between the jet 84 and the reflected refrigerant flow 86 resulting in turbulent flow within the inlet header volume. Turbulence within the inlet header can be enhanced by including turbulators (e.g., multifaceted flow interrupters) which can result in further turbulating the refrigerant flow 82.

When the microchannel heat exchanger 100 is configured for operation in a vapor compression system as an evaporator, the methods of operation can further include, jetting the refrigerant flow 82 through the fluid distribution conduit 50 at a first temperature and returning the refrigerant flow 82 to the refrigerant system at a second temperature (e.g., where the second temperature is greater than the first temperature). For example, the refrigerant flow 82, from the vapor compression cycle, can include cold refrigerant which is heated as it traverses the microchannel heat exchanger 100 by an airflow simultaneously passing across external surfaces of the microchannel heat exchanger 100, thereby simultaneously cooling the air and heating the refrigerant flow 82 therein.

The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.

While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims. 

What is claimed is:
 1. A microchannel heat exchanger comprising: an inlet header enclosing an inlet header volume and comprising an inlet port, and wherein the inlet header extends along a first direction; an outlet header; a plurality of microchannel tubes extending between, and fluidly connecting the inlet header and the outlet header; and a flow distribution conduit extending into the inlet header volume, interposed between, and in fluid communication with, the inlet port and the plurality of microchannel tubes and wherein the flow distribution conduit is configured to direct a fluid flowing therethrough along the first direction.
 2. The microchannel heat exchanger of claim 1, wherein the flow distribution conduit comprises the terminal end of a heat exchanger inlet pipe fluidly connecting the microchannel heat exchanger to a refrigerant containing system.
 3. The microchannel heat exchanger of claim 1, wherein the heat exchanger inlet pipe comprises a bend adjacent the flow distribution conduit.
 4. The microchannel heat exchanger of claim 3, wherein an angle of the bend is greater than or equal to 30 degrees and less than or equal to 150 degrees.
 5. The microchannel heat exchanger of claim 1, wherein the inlet header further comprises an inlet header length extending in the first direction and the flow distribution conduit extends into the inlet header volume an extension distance and wherein the extension distance is between 1% and 99%, endpoint inclusive, of the inlet header length.
 6. The microchannel heat exchanger of claim 5, wherein the extension distance is between 5% and 75%, endpoint inclusive, of the inlet header length.
 7. The microchannel heat exchanger of claim 5, wherein the extension distance is between 5% and 50%, endpoint inclusive, of the inlet header length.
 8. The microchannel heat exchanger of claim 1, wherein the flow distribution conduit comprises a flow distribution conduit inlet, a flow distribution conduit body, and a flow distribution conduit outlet, and wherein the flow distribution conduit body is impervious and configured without holes therethrough.
 9. The microchannel heat exchanger of claim 1, further comprising a hydraulic diameter ratio of the hydraulic diameter of the flow distribution conduit divided by the hydraulic diameter of the inlet header, and wherein the hydraulic diameter ratio is greater than or equal to 0.05 and less than or equal to about 0.95.
 10. The microchannel heat exchanger of claim 1, wherein the plurality of microchannel tubes comprises a bend or a fold such that the heat exchanger comprises a V shape, U shape, or A shape.
 11. The microchannel heat exchanger of claim 1, further comprising a turbulator disposed in the inlet header volume.
 12. The microchannel heat exchanger of claim 1, wherein the flow distribution conduit comprises a converging section and a throat.
 13. The microchannel heat exchanger of claim 1, wherein the microchannel heat exchanger is configured as an evaporator of a vapor compression cycle.
 14. The microchannel heat exchanger of claim 1, wherein the flow distribution conduit is positioned offset from a centerline of the inlet header volume.
 15. The microchannel heat exchanger of claim 14, wherein the offset is less than or equal to half the distance between the centerline of the inlet header volume and a wall of the inlet header.
 16. The microchannel heat exchanger of claim 1, wherein the inlet header and the flow distribution conduit are substantially cylindrical in shape.
 17. A vapor compression system comprising a compressor, an evaporator, a condenser, and an expansion valve, wherein the evaporator comprises the microchannel heat exchanger of claim
 1. 18. A method of distributing fluid in a heat exchanger comprising: providing a heat exchanger having an inlet header, an outlet header, and a plurality of microchannel tubes interposed between, and disposed in fluid communication with, the inlet header and the outlet header, wherein the inlet header comprises a fluid distribution conduit disposed between, and in fluid communication with, an inlet port and the plurality of microchannel tubes; jetting a refrigerant flow through the fluid distribution conduit into an inlet header volume of the inlet header; reflecting at least a portion of the refrigerant flow off an end cap of the inlet header; creating a shearing flow between the jetting flow and the reflecting flow thereby causing turbulent flow within the inlet header volume.
 19. The method of claim 18, further comprising: jetting the refrigerant flow through the fluid distribution conduit at a first temperature; and returning the refrigerant flow to the refrigerant system at a second temperature, wherein the second temperature is greater than the first temperature.
 20. The method of claim 19, further comprising changing the direction of the fluid flow before passing it through the fluid distribution conduit by forcing it through a bent section of pipe adjacent the fluid distribution conduit. 